Alongside pure voice links, modern mobile-radio devices can also perform multimedia data services, such as a video chat.
Before the use of such mobile-radio devices in a mobile radio network, the mobile-radio devices are tested with regard to their functional efficiency by the manufacturer and also by mobile-radio network operators.
By way of example, document EP 2 127 430 B1 describes a test method and a test device for testing such modern mobile-radio devices with a plurality of antennas. In this case, a test bit sequence is generated in a test device, converted, according to a given mobile-radio standard, into a test signal and transmitted to the mobile-radio device. The mobile-radio device receives the test signal and, taking into consideration the evaluated test signal, generates a response signal and specifies a transmission key for the transmission of the response signal to the test device.
These tests check the functions of the mobile-radio device which are necessary for the mobile-radio-specific transmission of the signals. Alongside these mobile-radio-specific functions, it is also necessary to check the functionalities for applications, such as the generation and reception of audio and/or video data, abbreviated here as audio/video data.
Not only can a mobile-radio device play back music and videos, it can also itself generate audio/video data. This is implemented, for example, by means of a camera and microphone. In this context, it is important to measure which processing rate (delay) the hardware and software internal to the mobile-radio device provides, in order to generate digital signals from the analog data. Furthermore, it is important to investigate whether the processing rate changes over time. This is also referred to as jitter. Other processing parameters such as packet error rates etc. are also relevant.
With existing tests, the time between the reading out of the audio/video data from a buffer in a test device and the playback of these audio/video data on a display of the mobile-radio device is conventionally measured, whereas, for example, the appearance of the data on the screen is registered by an external camera and the end time for the transmission is determined from this.
On the one hand, this has the disadvantage that additional devices, such as the camera, are required in order to determine the end time in the test system. On the other hand, the test device requires further functionalities, such as an encoder, a packer and functionalities for segmenting and formatting the data for a transmission with a protocol stack, in addition to the functionalities for the radio transmission via the mobile-radio network. These account for up to 50% of the processing time by the test device. Meaningful information about the actual processing rate of the audio/video data in the mobile-radio device itself is not available.
Accordingly, one object of the present invention is to provide a test system and a method with which processing parameters of audio/video data can be determined in a mobile-radio device without also needing to measure processing times outside the mobile-radio device, which are generated especially by audio/video functions in the test device.